1. Field of the Invention
This invention relates to an image processing system which is adapted to electronically interactive-edit images such as characters, designs, and binary images to process and image-record the same as a block copy for printing, further relates to a sampling method for data which is improved in performance by sampling image data for printing (density data) in a shorter time and reducing the time required for post-processing.
2. Description of the Prior Art
It has been heretofore desirable to provide an image processing system for typographers who require high quality printed matter in which characters, designs or the like are consolidated as a whole for editing the same. Notwithstanding, such system has not been proposed but is less capable and practical in use even if it is available.
Particularly, among others, a desk top publishing art has been gradually realized in a manner of description such as a post script but is still less capable and efficient of an image art. Systems for the typographers have been of course, available but is insufficient in handling (input, display, storage, processing, edition, and output and the like) data in bulk and at a high speed. This is because that the characters and images to be synthetically processed are subjected to various approaches by a description language, and a central processing unit (CPU; software) to thus exhibit a poor performance.
FIG. 1 is a flow chart showing a typical manufacturing process of a conventional print plate for printing, which comprises steps of inputting code data (Step S40) prepared by a word processor and the like, checking a PPC output after a code conversion (Step S41) of the code as prepared and a composing editing (Step S42), and outputting characters from a computer aided photocomposer (hereinafter referred to as "photocomposer") (Steps S43 and S44). What is termed the composing editing is meant to refer to arrangement of a row of the characters according to a prescribed rule, more specifically a forbidden processing or the like. In general, the word processor used for an office automation or the like is designed so that full scale characters are disposed in order. In contrast, the art of photocomposing is contemplated to obtain well-defined characters each of which is a half of the width of the full scale character. In this connection, it should be noted that the PPC output is a synonym for a laser beam printer (LBP). Generally, the output of the high quality image output unit is a black-and-white sensitized paper or film either of which is silver halide and expensive but functions at a speed lower than the LBP due to high resolving power. In contrast, the LBP is of less resolving power because of an electrophotographic system and is thus inexpensive but acts at a high speed. For this reason, the LBP is sufficient for checking and correcting layouts, characters or the like. The PPC output check is also meant to refer to confirmation of the characters or the like prior to the high quality image output without trial. The original for designs or the like is read out by a monotone scanner such as to output the image as screen dotted (Step S45). Computer aided and manual photocomposer character outputs, a line image, and an illustration and the like as well as such the screen dotted output are manually paste up (Step S50). A galley proof of its synthetic image is obtained to check its content and to correct it if necessary (Steps S51 and S52). Then, the manual photocomposer output for paste-up is provided to finally check and correct the image (Steps S54 and S55). These steps are followed by operations such as a camera work (Step S60), a page cutting (Step S61), a pinhole opaque (Step S62), and a film photo-composing (Step S63) for plate making. It is noted that disadvantages derived from the high quality image output unit are that the image outputted thereby to silver halide sensitive materials (such as a sensitive paper, a film or the like) is made white but not black or is turned adverse by a minute spot. These modifications and amendments are termed "pinhole amendments".
As seen from the foregoing, the conventional plate making process requires a great deal of operations such as repeated paste-up, photocomposing to involve much labor and time, thus considerably decreasing efficiency.
On the other hand, there have been known various sampling methods for data. For example, there has been proposed a sampling method comprising steps of reading picture images by a reading means to obtain image data of n bit/pixel, sampling the data or the density data while writing them in a buffer memory such as a disc or RAM as picture image data, processing the written data in accordance with the density, resolution and/or tone of an output unit or a display unit, and outputting them to a printer or the display unit.
However, the conventional sampling method is inconvenient as it takes a long time to process because the density data in n bit/pixel are written in the memory while sampling them simultaneously, and the amount of written data becomes enormous (e.g. in the case of data for the A4 size print-ready copy of 1000 dot/inch, the amount of data reaches as large as 120 Mbytes). If the data should be displayed, the processing such as thinning becomes necessary, and a large volume of data which are not essentially necessary have to be read out in a buffer.
Discs of the filing capacity of 300 Mbytes-3 Gbytes are usually used when picture images are written in as data. In order to write in the data in such a disc, the sampling pitch or the number of tones in A/D conversion of the data should be adjusted in accordance with the output unit, and the picture image data for one output are saved by one scanning in a writing-in unit. In order to newly prepare data for display purpose, the output unit should be scanned once more, requiring additional time.